In a general retail environment where groceries are sold, it is common for a point-of-sale (POS) terminal to include an item scanning device and for the item scanning device to have an integrated item weigh scale. The item scanning device scans an item presented to the POS terminal and if an optical code is found, reads the optical code and communicates the information to the POS terminal. The weigh scale determines the weight of one or more items placed on the weigh scale's “top plate” or “weigh plate” as it is sometimes referred to.
The top plate (horizontal surface) of a bi-optic item scanning device has a centered area composed of an optically transparent material to allow light, including laser light, to pass through. Whether the item scanning device is based on imaging or laser technology (or both), at least a portion of the top plate must allow light to pass through with a minimum of optical distortion and attenuation. This dictates the use of an optically clear material formed into a flat sheet with uniform thickness. The optically clear material is typically enclosed with a strong material for support. This material is can be a metal such as stainless steel. A top plate that meets these requirements is a major cost component of the item scanning device. In additional, items placed on the top plate will sometimes roll off or move around causing weighing errors or delays in reading the weigh of the item.
Thus, a need exists for a weigh scale device that has a lower cost top plate designed to center items placed on the top plate.